1. Field of the Invention
The present invention relates to a flexible synthetic resin tube for guiding a rod-like medical instrument such as a catheter or guide wire into a blood vessel to keep the rod-like medical instrument attached to the blood vessel.
2. Description of the Prior Art
A flexible synthetic resin tube is generally used for guiding, for example, a catheter into a blood vessel to keep the catheter attached to the blood vessel. As shown in FIG. 1, a syringe 2 is mounted to a guiding tube 1 such that the tip of the inner needle 3 of the syringe 2 projects through the distal end of the guiding tube 1. Then, the inner needle 3 is inserted into a blood vessel 4 until the distal end of the guiding tube 1 is positioned within the blood vessel 4. Further, the inner needle 3 is withdrawn from the blood vessel 4, with the guiding tube 1 left attached to the blood vessel 4, as shown in FIG. 2. In this condition, a catheter 5 is inserted through the guiding tube 1 such that the distal end portion of the catheter 5 is positioned within the blood vessel 4, as shown in FIG. 3. After the distal end portion of the catheter 5 is held within the blood vessel 4 as desired, it is desirable to withdraw the guiding tube 1 from the blood vessel 4 and from the catheter 5. It is undesirable from sanitary and operational view points to leave the guiding tube 1, which is no more useful, attached to the catheter 5.
However, it is impossible to withdraw the guiding tube 1 from the catheter 5 as the catheter 5 has an enlarged portion such as connector 6.
Under the circumstances, measures have been proposed for removing the guiding tube 1 from the catheter 5 after insertion of the distal end portion of the catheter 5 into the blood vessel 4. For example, it has been proposed to form in advance a slit in the guiding tube, in the longitudinal direction thereof, so as to remove the used guiding tube from the catheter along the slit. However, the slit may expand when the catheter is guided into the blood vessel causing leakage of the blood through the slit. To prevent the problem, the width of the slit must be restricted, making it difficult to remove the used guiding tube from the catheter.
U.S. Pat. No. 4,402,685 teaches that the guiding tube is provided with a pair of linear bodies facing each other in the radial direction of the tube and extending in the longitudinal direction of the tube. The linear bodies are formed of a plastic material which is heterogeneous from the plastic material forming the other part of the guiding tube. The proximal end portion of the guiding tube is inflated to provide the mounting part for the inner needle hub. The mounting part is provided with slits connected to the linear bodies. The guiding tube after use is split along the linear bodies by pulling the mounting part in opposite directions to split the slits. However, the linear bodies tend to crack during after-treatments such as cutting of the guiding tube or when the product guiding tube is handled, leading to uselessness or other serious problems such as blood leakage.